Oxidative Stress-Induced Microglial CD22 Upregulation Impairs Phagocytosis and Exacerbates Huntingtons Disease

Lee, Y. H.; Siew, J. J.; Lee, C.-W.; Chen, H.-M.; Lu, Y.-T.; Sridharan, D.; Huang, P.-C. J.; Chang, H.-C.; Guu, S.-Y.; Wang, P.-Y.; Wang, Y.-F.; Liang, S.-Y.; Khoo, K.-H.; Angata, T.; Chern, Y.

doi:10.64898/2026.03.11.710967

bioRxiv · 10.64898/2026.03.11.710967

Oxidative Stress-Induced Microglial CD22 Upregulation Impairs Phagocytosis and Exacerbates Huntingtons Disease

Lee, Y. H.·Siew, J. J.·Lee, C.-W.·Chen, H.-M.·Lu, Y.-T.·Sridharan, D.·Huang, P.-C. J.·Chang, H.-C.·Guu, S.-Y.·Wang, P.-Y.·Wang, Y.-F.·Liang, S.-Y.·Khoo, K.-H.·Angata, T.·Chern, Y.

View original source ↗Export metadata ↓

Abstract

BackgroundHuntingtons disease (HD) is a neurodegenerative disorder caused by an abnormal polyglutamine expansion in mutant huntingtin (mHTT) and is characterized by movement dysfunction and neuronal loss. Siglecs, a family of sialic acid-binding proteins, are expressed on brain microglia and implicated in Alzheimers disease. Sialic acids are abundant in mammalian brains and cap the termini of the glycocalyx of various brain cells. Alterations in sialoglycans or Siglecs may affect interactions between microglia and other brain cells. However, the roles of Siglecs in HD have not been investigated. MethodsWe profiled Siglecs in postmortem caudate nucleus samples from HD subjects and in a mouse model of HD (R6/2) using RT-qPCR and mass cytometry analyses. CD22 functions in microglia were evaluated using a microglial cell line (BV2) and primary microglia. Native ligands for microglial CD22 were assessed via glycomic profiling and flow cytometry. Regulation of CD22 ligands in astrocytes was investigated in an astrocytic cell line (C8-D1A) and primary astrocytes. The role of CD22 in HD was examined by genetic deletion in HD mice, followed by behavioral analyses and pathological evaluation with immunofluorescence staining and MRI. ResultsUpregulation of CD22 in microglia, observed in the brains of patients and mice with HD, impairs microglial phagocytosis via ITIM-ITAM signaling crosstalk. This CD22 upregulation was driven by chronic oxidative stress, as antioxidant treatment (N-acetylcysteine) markedly normalized CD22 levels. CD22 ligand, 2,6-sialylated-6-sulfo-LacNAc, primarily expressed by astrocytes, was significantly reduced in HD mice. mHTT, but not wild-type HTT, suppressed ligand synthesis in astrocytes under elevated oxidative stress, allowing more CD22 on the microglial surface to inhibit phagocytosis. Treatment with a neutralizing antibody or ligand-enriched extracellular vesicles depleted surface CD22 and restored the phagocytic function of microglia. Genetic deletion of CD22 in HD mice improved rotarod performance, reduced mHTT inclusion burden, increased Darpp32 expression, and alleviated brain atrophy, supporting the concept that CD22-mediated inhibition of microglial phagocytosis contributes to HD pathogenesis. ConclusionOur findings suggest that CD22 acts as a checkpoint-like regulator that restrains microglial phagocytosis and contributes to HD progression when astrocyte-microglia communication is impaired, thereby highlighting CD22 as a promising therapeutic target.

Explore related subjects

neuroscience Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Lee, Y. H., Siew, J. J., Lee, C.-W., Chen, H.-M., Lu, Y.-T., Sridharan, D., Huang, P.-C. J., Chang, H.-C., Guu, S.-Y., Wang, P.-Y., Wang, Y.-F., Liang, S.-Y., Khoo, K.-H., Angata, T., Chern, Y.. 2026-03-13. Oxidative Stress-Induced Microglial CD22 Upregulation Impairs Phagocytosis and Exacerbates Huntingtons Disease. https://doi.org/10.64898/2026.03.11.710967

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Isogenic forebrain organoids uncover early neurodevelopmental alterations and imbalances in neuronal function leading to hyperexcitation in Gaucher disease

Gaucher disease is a rare lysosomal storage disorder caused by autosomal recessive mutations in the GBA1 gene, encoding the lysosomal enzyme glucocerebrosidase. Gaucher disease is classified in 3 different subtypes depending on the presence and severity of neurological involvement, with type 2 resulting in fatal early-onset neuropathology and patients exhibiting developmental delays, seizures and early death. Studies investigating disease mechanisms of neuronopathic Gaucher disease are mainly based on animal models and focus predominantly on late neuronal phenotypes. Here, we established healthy control and Gaucher disease patient-derived iPSC lines and engineered them to obtain isogenic control and disease lines. Using these lines, we generated cortical and subpallial brain organoids in which we identified early-onset lipid dysregulation in form of glucosylceramide accumulation, highly elevated glucosylsphingosine, and a later increase in ganglioside levels, recapitulating clinical findings. Furthermore, single-cell transcriptomic profiling uncovered novel phenotypes in both cortical and subpallial forebrain organoids. Subpallial alterations consisted of an early increase in migrating interneurons in subpallial organoids, which upregulated cholesterol metabolism. Cortical alterations showed early upregulation of mitochondrial genes and a downregulation of proliferation, with a subsequent switch from GABAergic to glutamatergic neuron fate with a striking increase in gene expression related to the synaptic assembly. Functional assays demonstrated a marked hyperexcitability of cortical organoids and reduced response to GABA-A receptor blockage in Gaucher disease. Additional 2D neuronal network models confirmed the organoid data and showed that both glutamatergic and GABAergic neurons contribute to the phenotype, with hyperexcitability of Gaucher glutamatergic neurons and incapacity of Gaucher GABAergic neurons to balance the excessive excitation. This alteration represents a clinically significant phenotype as many patients exhibit an excitation/inhibition imbalance leading to treatment-resistant seizures, hastening their decline. In conclusion, our defined human models of Gaucher disease identify novel and clear phenotypes that can be used for drug screening or aid in development of new therapeutic strategies to ameliorate Gaucher disease.

neuroscience↗

bioRxiv2026

Oxytocin and Vasopressin Immunoreactivity Differs Across Auditory Brainstem Nuclei in Rodents with Distinct Social Systems

Oxytocin (OT) and vasopressin (AVP) are neuropeptide hormones involved in regulating animal social behavior and a broad spectrum of physiological processes. Although their distributions are well documented in neuroendocrine regions of the forebrain and midbrain, their expression in the hindbrain remains poorly understood. Here, we used immunohistochemistry to quantify OT and AVP immunoreactive puncta within three auditory brainstem nuclei, the lateral superior olive (LSO), the medial superior olive (MSO), and the medial nucleus of the trapezoid body (MNTB) in six wild-caught rodent species differing in sociality. We also quantified the volume of these nuclei and examined variation in total brain volume across species and sociality. OT and AVP puncta count differed among species and social groups. Group-living species exhibited higher OT and AVP puncta counts than monogamous and solitary species in the LSO and MNTB. In the MSO, OT puncta counts did not differ among social groups, whereas AVP puncta counts were higher in group-living than in monogamous and solitary species. Total brain volume and the volumes of the MNTB and MSO differed among species, but not across social groups, whereas LSO volume did not differ among species or sociality. These findings revealed sociality-related variation in OT and AVP immunoreactive puncta within auditory brainstem circuits and suggest that neuropeptide signaling within early auditory brainstem pathways may contribute to the neural integration of social and auditory information.

neuroscience↗

bioRxiv2026

Connexin 40 deficiency alters the temporal profile of postictal oxygen dynamics following focal seizures.

Epilepsy is increasingly recognized as a disorder involving both neuronal and vascular dysfunction. While connexin signaling has been implicated in epileptogenesis, the contribution of vascular connexins to seizure associated cerebrovascular pathology remains poorly understood. Connexin40 (Cx40) is an endothelial gap junction protein that plays a crucial role in vascular communication and blood-flow regulation. Seizures induce dynamic changes in cerebral perfusion and oxygenation, including prolonged postictal hypoperfusion/hypoxia. To determine whether Cx40 influences postictal hypoxia following focal seizures, we examined seizure characteristics and postictal oxygen dynamics in Cx40 knockout (Cx40-/-) mice using an established focal hippocampal seizure model. Electrically kindled seizures were elicited in wild-type and Cx40-/- mice, and local hippocampal tissue oxygenation was continuously monitored before and after seizure induction. Seizure duration did not differ between genotypes, indicating comparable seizure severity. Interestingly, Cx40 deletion altered the temporal pattern of postictal oxygen recovery, producing greater early hypoxia and a delayed secondary rebound in pO2 despite similar peak oxygen levels and overall hypoxic burden. These findings demonstrate that loss of Cx40 selectively alters the temporal profile of postictal oxygen dynamics without affecting seizure duration. Taken together, the results suggest that endothelial gap junctional communication contributes to postictal vascular recovery and identify Cx40 as a potential modulator of seizure associated neurovascular dysfunction.

neuroscience↗